The lithium ion batteries installed on the Boeing 787 are inherently unsafe, says Elon Musk, founder of SpaceX and owner of electric car maker Tesla."Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," writes Musk in an email to Flightglobal."Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature," he adds.Both Boeing and Tesla use batteries fueled by lithium cobalt oxide, which is among the most energy-dense and flammable chemistries of lithium-ion batteries on the market. While Boeing elected to use a battery with a grouping of eight large cells, Tesla's batteries contain thousands of smaller cells that are independently separated to prevent fire in a single cell from harming the surrounding ones."Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire," says Musk.

An aerospace-capable version of Tesla's battery has been developed for use in SpaceX's Falcon 9 space launch vehicle. SpaceX, also owned by Musk, competes with Boeing/Lockheed Martin joint venture United Launch Alliance for customers. Boeing has thus far declined offers of assistance from Tesla and SpaceX, says Musk."They [Boeing] believe they have this under control, although I think there is a fundamental safety issue with the architecture of a pack with large cells," writes Musk in an email. "It is much harder to maintain an even temperature in a large cell, as the distance from the center of the cell to the edge is much greater, which increases the risk of thermal runaway."

Musk's assessments of battery cells were confirmed by Donald Sadoway, a professor of electrical engineering at the Massachusetts Institute of Technology."I would have used the same words," says Sadoway. "I would have used the same words. I'm glad someone with such a big reputation put it on the line.""He's engineered [Tesla's battery] to prevent the domino effect, while Boeing evidently doesn't have that engineering," adds Sadoway.As a fleet-wide grounding enters its third week, the battery failures on 787s flown by Japan Airlines and All Nippon Airways eariler this month remain under investigation by the US National Transportation Safety Board. Japanese inspectors have cleared the maker of the battery, GS Yuasa, of any defects before the unit leaves the factory. But both Japanese and US investigators continue to examine and test the batteries to understand why they failed after they were integrated into the 787 electrical system and operated on commercial flights.

The NTSB, for example, has began a detailed examination of an undamaged 787 battery at a US Navy laboratory, hoping to "uncover signs of any degradation in expected performance".Investigators are trying to find the answer to a problem that eluded Boeing and the FAA in the certification phase, even though the manufacturer and the regulator were well aware of the risks posed by lithium-ion batteries.Mike Sinnett, Boeing's 787 chief project engineer, explained the careful design philosophy employed for the 787's battery system, the first to serve as a starter for an auxiliary power unit and emergency power back-up in a commercial aircraft."I design a cell to not fail and then assume it will and the ask the next 'what-if' questions," Sinnett said. "And then I design the batteries that if there is a failure of one cell it won't propagate to another. And then I assume that I am wrong and that it will propagate to antoher and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."

Oddly enough, the Japanese claim there's nothing wrong with the battery (which just so happens to be designed in Japan).

Dreamliner: No fault found with Boeing 787 battery

Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said.

The battery was initially considered the likely source of problems on 787s owned by two Japanese airlines.

It has raised fears that there will be no quick fix to a problem that meant all 50 787s in service were grounded.

Attention has now shifted to the electrical system that monitors battery voltage, charging and temperature.

Transport ministry official Shigeru Takano said "we have found no major quality or technical problem" with the lithium-ion batteries. Shares in GS Yuasa, which makes the batteries, jumped 5% on the news.

"We are looking into affiliated parts makers," he said. "We are looking into possibilities."

The safety investigation started after one of the 787s operated by All Nippon Airways made an emergency landing in Japan when its main battery overheated. Earlier, a battery in a Japan Airlines 787 caught fire while parked at Boston's Logan International Airport.

Zafar Khan, aviation analyst at Societe Generale, said: "The obvious implication is that it may prolong the grounding.

"If it's not the battery then we are back to the drawing board. We know it's an electrical - and not a structural - issue and that will be the focus for the inspectors. But there's a lot of cabling on these aircraft."

'Fingers crossed'

Keith Hayward, head of research at the Royal Aeronautical Society, said that if the issue is no longer about replacing a faulty battery, it raised the prospect of Boeing having to do a major re-design.

"I think people had their fingers crossed that it was a battery fault... it looks more systemic and serious to me. I suspect it could be difficult to identify the cause," he said.

He added that aviation regulators will have to put the 787 through another airworthiness certification process, which itself could become a complicated and lengthy process depending on the final cause of the problem.

Two weeks ago the US Federal Aviation Administration said both batteries had leaked electrolyte fluid, and there had been smoke damage to parts of the aircraft.

The FAA said airlines must demonstrate battery safety before flights could resume, a statement that effectively meant airlines had to ground their 787s.

Boeing, which competes against Europe's Airbus, has halted 787 deliveries. Boeing has orders for more than 800 Dreamliners.

The 787 is the first airliner made mostly from lightweight composite materials, which increases an aircrafts fuel efficiency. It also relies on electronic systems rather than hydraulic or mechanical systems to a greater degree than any other airliner.

Compensation

Mr Khan said that most analysts had forecast that the 787 would be out of service for, perhaps, eight weeks at most. Beyond 10-12 weeks, and it could impact on Boeing's production line and future deliveries, he said.

"That raises questions of damages (to airlines) for late delivery and the leasing of alternative aircraft," he said.

Last week, analysts at Bernstein put the cost of fixing the Dreamliner at about $350m (£222m). Meanwhile, Jefferies estimated the likely cost at between $250m to $625m. But that was before the likely primary cause - the battery - was ruled out.

Depending on the cause of the problem, Boeing might be able to recoup any costs from suppliers. But analysts say that the longer the issue continues, the higher the risk for Boeing, suppliers, jobs, and investors.

On Wall Street, Boeing shares opened almost 1% down and are more than 4% lower since the issue came to light. "The amazing thing is that the share price has held up so well," said Mr Khan.

Its a shame this. The 787 is probably one of the safest flying machines around, yet due to efficiency and space, the lithium cell may just be its downfall. Fearsome in everyday use, such as laptops, mobiles etc, but 'deadly' as part of today's commercial flying.

The use of smaller, physically isolated LiIon cells is one of Tesla & SpaceX's better ideas. They set the cell size to a tad larger than a AA battery, limiting the amount of energy in a failed cell that needs to be dissipated. Other battery makers use much larger prismatic or cylindrical cells that would generate tons more heat if they fail. Individual cells can also be electrically isolated from the rest of the stack if a problem is detected. Tesla's cells are fabbed by Panasonic to their specs.

Late reports are that it was the electrinics / wiring, but Musk is still correct that the battery design is suboptimal.

Of course it is. The same **** happened when GS Yuasa tested the 787 batteries a couple of years ago and it looks like they didn't change anything from it.

Not to mention, the outsourcing done on the 787 is crazy.

This battery was contracted to be designed and built in Japan. Instead what happened was the battery was designed in Japan, manufactured in China and then shipped to France (Thales Communications) where it was put together and had some bits added on before being sent to Boeing.

The wing ribs were originally going to be made in Japan but that company sold the contract to Hyundai who sold it to a Chinese company.

Now, investigators at the National Transportation Safety Board have determined the cause of the battery fire in the Japan Airlines 787, saying that the fire was caused by a short circuit in one of the battery’s cells leading to a thermal runaway which led to the other cells catching fire. The NTSB said that temperatures inside the battery exceeded 260 degrees Celsius (500 degrees Fahrenheit).>

Japan's transport safety board said a whole two days after the grounding that there was nothing wrong with the batteries and they were fine. And now the NTSB says the batteries do have flaws. Not to mention that this same issue happened in 2007 during testing with the same batteries that GS Yuasa then dumped into the 787. Trying to protect Japanese companies eh JTSB?

Another story in the 787's saga, apparently the FAA contracted out 90% of the safety / certification stuff to Boeing in order to save costs. So in essence Boeing engineers were the ones vouching for the safety of the plane.

In comparison, say you built your own kit airplane and wanted to get it certified. You'd call up the FAA and an inspector will come over to check it. This is for a tiny plane that can't be used for hire (and has a bunch of other restrictions too).

The tests on the lithium-ion batteries at the center of Boeing’s unprecedented crisis were conducted by the company. And the people the FAA designated on its behalf to ensure that the batteries conformed to its safety regulations also were Boeing employees.

In a 2011 review, the inspector general of the Department of Transportation found the FAA in one case delegated some 90 percent of the determination for regulatory compliance for new aircraft design to outside representatives. The Inspector General’s Office would not identify the company, but the report focused on Boeing, Cessna Aircraft and Bombardier-Learjet.

Among other things, the FAA required the battery design to prevent the possibility of spreading, uncontrolled overheating. That danger, known as thermal runaway, is exactly what occurred in the first of two 787 incidents, when a fire broke out aboard a Japan Airlines 787 after it landed in Boston’s Logan Airport on Jan. 7. The National Transportation Safety Board (NTSB) said the battery showed signs of short-circuit and thermal runaway.

The FAA also had decreed that any battery malfunction not damage surrounding electrical systems and equipment enough to cause a more serious failure. Yet the Japanese plane sustained damage to the adjacent electronics bay, although the NTSB has yet to determine whether the battery — located beneath the cabin in the plane’s rear and accessible only from the outside — could have disabled critical flight controls had the fire occurred in midair.

Meanwhile, SpaceX & Tesla engineers took on the responsibility themselves; making their own judgements based on rational self-interest, which appear to be very sound, speccing to Panasonic exactly what they wanted. They are now not only driving the roads with them but flying them in the harshest environments of all - space launches & flight.